This invention relates to a distributor type fuel injection pump having in one embodiment opposed reciprocating plungers mounted in a housing to provide pressurized fluid to a rotor which in turn provides fuel metering, distribution, and timing of the fuel delivery to an internal combustion engine.
This invention is particularly directed toward a distributor fuel injection pump which is capable of a high fueling capacity in a small overall size for use on large internal combustion engines particularly the compression ignition type engines. Previous pumps utilized on large engines such as this have required separate injection pumps for each cylinder or a very large distributor pump. Although this pump is designed with a high capacity for large engines, it is easily adaptable to smaller engines by changing the porting structure and internal passage size without a major redesign of the fuel pump.
Fuel pumps in the past of the types described have utilized reciprocating plungers but have had rather complex camming surfaces. Such complex camming surfaces and cam slippers have limited the quantity and pressure of fuel injected because of excessive cam stress. This has tended to restrict the use of distributor pumps to relatively small engines.
Particular problems associated with all fuel injection pumps of the type described herein include a requirement for a relatively high pressure to be communicated to the engine cylinder for ignition therein by compression. Fuel must be communicated to the engine cylinder at a particular time in order to achieve optimum performance of the engine. Fuel also must be delivered to the engine in correct quantity as dictated by the power required to maintain a desired operating speed. Amounts of fuel communicated to the engine obviously must vary according to the engine load. Thus, a distributor type fuel injection pump must serve initially to pressurize the fuel, and secondly to meter the fuel as required. It is also appropriate to vary the injection timing in proportion to engine speed.